川南丘陵区近30 a来土壤养分时空变化

目的]通过研究川南丘陵地区区域尺度上土壤养分的空间分异特征和时间变化特点,为该区域的土壤质量管理和农业可持续发展服务。方法]基于GIS技术和地统计学方法,分析1982—2011年川南丘陵地区宜宾市南溪区长兴镇耕地土壤有机质、全氮、碱解氮、有效磷、速效钾的时空变化情况。结果](1)研究区5种土壤指标中,有效磷的变异系数最高,其余指标变异系数在22.18%~37.03%,属中等程度变异。(2)结构分析表明,1982年时土壤养分的块基比为25%~75%,属中等变异,结构因素和人为因素对其都有影响;到了2011年,各指标空间自相关性变弱,人为因素占主导作用。(3)克里格插值显示,研究区近1/2区域土壤氮素偏高,全氮和碱解氮含量在高等级及以上面积分别占39.26%和47.94%;磷素虽略有上升,但有52.68%的区域有效磷含量在5mg/kg以下,属严重缺磷;钾素含量在中上等级区域面积减少,大部分在中下水平,甚至出现了极低水平。结论]经过近30a土地利用后,整体上研究区土壤养分北高南低,且呈重氮,轻磷,忽钾的态势,研究区以南要注意控制氮肥的输入,补充磷、钾肥。

Spatial and Temporal Change in Soil Nutrients in Hilly Area of Southern Sichuan Basin in Past 30 Years

Objective] The spatial and temporal changes in soil nutrients in hilly area of Southern Sichuan basin was investigated in order to provide support for the soil quality management and the agricultural sustainable development.Methods] Using the data of the second soil survey in 1982 and the soil fertility monitoring data in 2011, the article analyzed spatial and temporal changes in soil nutrients in Changxing township, Yibin City under the SPSS 17.0 and ArcGIS 9.3 platforms.Results] (1) Among the five soil indicators, the highest coefficient of variation was available phosphorus, the rest indexes varied between 22.18% to 37.03%, indicating a moderate variation.(2) Semivariogram analyses indicated that the nugget/sill of soil nutrients ranged from 25% to 75% in 1982, showing a medium variation. Both of the structural and human factors had influence on it. In 2011, the spatial autocorrelation of each index was weak, and the human factor played a dominant role.(3) The ordinary Kriging interpolation showed that nearly half of the study area have high nitrogen, and the area with total nitrogen and alkali-hydrolyzable nitrogen content in high grade and above accounted for 39.26% and 47.94% respectively. Although phosphorus increased slightly, the content of available phosphorus below 5 mg/kg accounted for 52.68% of the area, indicating a serious phosphorus deficiency. The potassium content in the area of an upper-middle class reduced, mostly in the middle and lower levels, or even extremely low levels.Conclusion] After nearly 30 years of land use, the soil nutrient in the northern area is higher than in the south, with more emphasis on nitrogen and little on phosphorus and potassium fertilizer. More effots should be devoted to limiting inputs of nitrogen and adding phosphorus and potassium in the south of the study area.